Recent trends toward economically fabricating vehicle structures while ensuring structural performance have led to the use of toughened structural adhesive polymers in the automotive industry. Structural adhesives are adhesives that generally exhibit good load-carrying capability, long-term durability, and resistance to heat, solvents, and fatigue. Toughened structural adhesive polymers are structural adhesives in which elastomeric particles are added or other means are used to increase the toughness of the polymer. Adhesive bonding of vehicle structures, such as, for example, metal vehicle structures, typically involves the use of structural adhesive polymers along with other means of joining the structures, such as by resistance spot welding or other assembly techniques, or riveting or other mechanical fastening techniques. The use of toughened structural adhesive polymers has been shown to offer better fatigue performance and greater flexibility in joining dissimilar materials when compared with, for example, resistance spot welding alone.
While a significant effort has been focused on developing toughened structural adhesive polymers, there is a need to understand the effects of various design variables on the performance of adhesively-bonded components. Furthermore, to facilitate the use of advanced high strength metals for lighter and stronger vehicles and vehicle joints, more cost-effective vehicle structure design guidelines and predictive capability of the dynamic performance of toughened adhesive-bonded joints are required. The development of such guidelines and predictive capability depends not only on an understanding of the impact characteristics of the metals but also the impact behavior of the toughened structural adhesives. While there is some understanding of the stress-strain relationship of toughened structural adhesives when subjected to impact strains at room temperature, information regarding the stress-strain relationship of toughened structural adhesive polymers when subjected to impact strains at various strain rates and at temperatures other than room temperature is still in high demand.
Accordingly, it is desirable to provide methods for estimating the stress of a toughened structural adhesive polymer when subjected to a selected strain at a selected strain rate and at a selected temperature. In addition, it is desirable to provide a program product for estimating the stress of a toughened structural adhesive polymer subjected to a selected strain at a selected strain rate and at a selected temperature. It also is desirable to provide a system for estimating the stress of a toughened structural adhesive polymer subjected to a selected strain at a selected strain rate and at a selected temperature. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.